TY - JOUR
T1 - Effect of composition of La0.8Sr0.2MnO3-Y2O 3-stabilized ZrO2 cathodes. Correlating three-dimensional microstructure and polarization resistance
AU - Wilson, James R.
AU - Cronin, J. Scott
AU - Duong, Anh T.
AU - Rukes, Sherri
AU - Chen, Hsun Yi
AU - Thornton, Katsuyo
AU - Mumm, Daniel R.
AU - Barnett, Scott
N1 - Funding Information:
The authors gratefully acknowledge the financial support of the National Science Foundation Ceramics program through grants DMR-0542740 (Northwestern Univ.) and 0645812 (UC-Irvine). The authors also acknowledge the use of the facilities within the Carl Zeiss Center of Excellence at the University of California, Irvine as well as Marcio Gameiro for his work involving the connectivity calculations.
PY - 2010/4/2
Y1 - 2010/4/2
N2 - Composite La0.8Sr0.2MnO3 (LSM)-Y2O3-stabilized ZrO2 (YSZ) cathodes with compositions ranging from 30:70 to 70:30 wt.% LSM:YSZ were studied both electrochemically and microstructurally. Polarization resistance was lowest for the 50 wt.% YSZ composition, and increased symmetrically as the composition deviated from this value. Serial-sectioning using focused ion beam-scanning electron microscopy was implemented to reconstruct the three-dimensional cathode microstructure. Various averaged structural parameters were determined versus composition, including phase volume fractions, surface area densities, total triple-phase boundary (TPB) densities, interfacial curvatures, phase tortuosities, and the levels of phase connectivity. Typically >90% of the pore and YSZ networks were found to be intra-connected to the surrounding phase, but the LSM networks showed lower connected fractions, as low as 37.5% for a LSM weight fraction of 30%. The composition dependences of the total TPB density and electrochemically-active TPB density (i.e., TPB's on three fully intra-connected phases) were shown to agree reasonably well with simple "sphere-packing" structural models. An electrochemical model that accounted for the linear-specific resistance of TPB's, phase intra-connectivity, and oxygen ion transport in the YSZ as influenced by its tortuosity, was found to provide reasonable agreement with the measured polarization resistance versus composition.
AB - Composite La0.8Sr0.2MnO3 (LSM)-Y2O3-stabilized ZrO2 (YSZ) cathodes with compositions ranging from 30:70 to 70:30 wt.% LSM:YSZ were studied both electrochemically and microstructurally. Polarization resistance was lowest for the 50 wt.% YSZ composition, and increased symmetrically as the composition deviated from this value. Serial-sectioning using focused ion beam-scanning electron microscopy was implemented to reconstruct the three-dimensional cathode microstructure. Various averaged structural parameters were determined versus composition, including phase volume fractions, surface area densities, total triple-phase boundary (TPB) densities, interfacial curvatures, phase tortuosities, and the levels of phase connectivity. Typically >90% of the pore and YSZ networks were found to be intra-connected to the surrounding phase, but the LSM networks showed lower connected fractions, as low as 37.5% for a LSM weight fraction of 30%. The composition dependences of the total TPB density and electrochemically-active TPB density (i.e., TPB's on three fully intra-connected phases) were shown to agree reasonably well with simple "sphere-packing" structural models. An electrochemical model that accounted for the linear-specific resistance of TPB's, phase intra-connectivity, and oxygen ion transport in the YSZ as influenced by its tortuosity, was found to provide reasonable agreement with the measured polarization resistance versus composition.
KW - Cathodes
KW - Focused ion beam (FIB) tomography
KW - Solid oxide fuel cells
KW - Three-dimensional (3D) microstructure
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U2 - 10.1016/j.jpowsour.2009.09.074
DO - 10.1016/j.jpowsour.2009.09.074
M3 - Article
AN - SCOPUS:71549168925
SN - 0378-7753
VL - 195
SP - 1829
EP - 1840
JO - Journal of Power Sources
JF - Journal of Power Sources
IS - 7
ER -
